code: def forward(
      self,
      input: torch.Tensor,
      ilens: torch.Tensor,
      fs: int = None,
  ) -> Tuple[torch.Tensor, torch.Tensor]:
      raise NotImplementedError
  
file_path: espnet/espnet2/enh/encoder/abs_encoder.py
imports: from abc import ABC, abstractmethod
  from typing import Tuple
  import torch
label_desc: Use image node_id 1 for calling the AbsEncoder obj's underlying member method code with example usage: obj.forward(input, ilens, fs) without return types